Selective Fluorescence Turn-on Sensor Research Articles

Highly selective fluorescence turn-on sensor for·thiol compounds detection

As a kind of commonly-used synthetic materials for many pesticides, thiol compounds, once being leaked, can cause serious harm to the environment and humans. Therefore, the efficient detection of thiol compounds is essential. In this study developed a turn-on fluorescent probe (Cu@Zn-CP) for the highly sensitive fluorescence detection of thiol compounds. The probe was constructed based on a zinc coordination polymer (Zn-CP), whose fluorescence was quenched through the effective doping of Cu2+ ions. After the introduction of methyl thioglycolate (MTC), a rapid fluorescence turn-on response was generated within 90 s with a low detection limit of 23 ppb. Even after being reused for five cycles, the sensor maintains excellent detection performance and demonstrates good recyclability. It can also detect MTC in river water, with a spike recovery rate between 98–103 %. Furthermore, the designed Cu@Zn-CP exhibits good universality for detecting multifarious thiol compounds, including L-cysteine, glutathione, monothioglycerol, and 2-hydroxy-1-ethanethiol. This result provides a potential recyclable fluorescent sensor for thiol compounds.

A versatile sensor capable of ratiometric fluorescence detection of trace water and turn-on detection of Cu2+ modulating the binding interaction of a Cu(II) complex with BSA and DNA complemented by docking studies.

A fluorescent molecule, pyridine-coupled bis-anthracene (PBA), has been developed for the selective fluorescence turn-on detection of Cu2+. Interestingly, the ligand PBA also exhibited a red-shifted ratiometric fluorescence response in the presence of water. Thus, a ratiometric water sensor has been utilized as a selective fluorescence turn-on sensor for Cu2+, achieving a 10-fold enhancement in the fluorescence and quantum yield at 446 nm, with a lower detection limit of 0.358 μM and a binding constant of 1.3 × 106 M-1. For practical applications, sensor PBA can be used to detect Cu2+ in various types of soils like clay soil, field soil and sand. The interaction of the PBA-Cu(II) complex with transport proteins like bovine serum albumin (BSA) and ct-DNA has been investigated through fluorescence titration experiments. Additionally, the structural optimization of PBA and the PBA-Cu(II) complex has been demonstrated by DFT, and the interaction of the PBA-Cu(II) complex with BSA and ct-DNA has been analyzed using theoretical docking studies.

A highly selective fluorescence turn-on sensor for Hg2+ based on quinolimide in aqueous media and its applications

Herein, a novel fluorescent sensor QPE based on quinolimide was developed, which displayed the highly selective response to Hg2+ through the turn-on signal in aqueous media. The corresponding recognition mechanism of QPE for Hg2+ was investigated by the titration experiments, Job’s plots, HRMS, and DFT calculations analysis. QPE could detect Hg2+ in a broad pH range (pH = 4–9) with the LOD of 20 nM and the LOQ of 66 nM. Meanwhile, QPE-loaded test strips were demonstrated in the visual detection of Hg2+. Importantly, QPE exhibited the reliable capability to track Hg2+ in real water and soil samples and yeast cells, indicating that QPE could be used as a prospective tool for monitoring Hg2+ in wide fields.

Fluorescent Turn-On Sensing of Zinc(II) and Alkaline Phosphatase Activity Using a Pyridoxal-5'-Phosphate Derived Schiff Base.

A novel Zn2+ ion and alkaline phosphatase (ALP) selective fluorescence turn-on sensor L was developed by reacting pyridoxal 5'-phosphate (PLP) with hydrazine. Sensor L shows significant flurescence enhancement at 476nm due to the formation of a L-Zn2+ complex in 1:1 binding stoichiometry with the association constant of 3.1⋅104M- 1. Using L, the concentration of Zn2+ can be detected down to 2.34 µM, and the practical utility of L was validated by quantifying Zn2+ in real water samples. Additionally, the receptor L was applied to mimic the dephosphorylation reaction catalysed by the enzyme ALP and the resulted fluorescence change was monitored to detect the ALP activity.

Molecular phosphonic acid-tethered tetraphenylethene AIEgen based highly selective fluorescent turn-on sensor for neomycin

We demonstrated highly selective and sensitive tetraphenylethene -tetraphosphonic acids for the facile detection of aminoglycoside antibiotic neomycin for the first time. Neomycin was found to effectively induce aggregate formation of (4-(1,2,2-tris(4-phosphonophenyl)vinyl)phenyl)phosphonic acid octasodium salt (TPPE) in aqueous solution. The aggregation-induced emission (AIE) response of TPPE was realized upon addition of neomycin in Milli-Q water at pH 7. The detection mechanism relies on electrostatic and hydrogen bonding interactions. The TPPE-based sensor system exhibited a detection limit 2.088 × 10−10 M of neomycin. Further, we demonstrate use of TPPE system for visual detection of neomycin as thin layer chromatography (TLC) sensor to develop kits for real world applications.

Phenanthroimidazole and dicyanovinyl-substituted triphenylamine for the selective detection of CN−: DFT calculations and practically applications

A novel CN− selective fluorescent turn-on sensor (TPMN) possessing triphenylamine and phenanthroimidazole as signaling units and dicyanovinyl unit for the binding site was designed and synthesized. TPMN exhibited a drastic change in its emission spectra with about 13-fold fluorescence enhancement when treated with CN−, while other tested anions could not arouse the fluorescence enhancement. The experimental and theoretical calculation results showed that this increase in fluorescence intensity of TPMN in presence of CN− is due to the large decrease in the ICT effect by the addition of CN− ion to β-carbon of the dicyanovinyl moiety. TPMN could selectively detect CN− with a detection limit of 0.23 μM among the common anions. The CN−-binding mode was well-characterized to be 1:1 by using Job’s plot with an association constant of 5.36 (logKa). Besides, the possible utilization ofTPMN was successively tested in water samples and test kits.

An efficient J-aggregate based fluorescence turn-on and ratiometric sensor for heparin

Heparin is the second most widely used natural drug and an extensively employed blood anticoagulant worldwide. Construction of fluorescent sensors for Heparin has remained heavily dependent on the complex and time-consuming laborious synthetic efforts. However, reports on the direct usage of in-expensive commercially available probe molecule, for sensitive and selective fluorimetric sensing of Heparin, which can greatly simplify the synthetic efforts, has been limited and remains highly desirable. Herein, we report a very sensitive and selective fluorescence turn-on sensor for Heparin, which utilizes a commercially available organic dye molecule, Pseudoisocyanine. The supramolecular interaction between the Pseudoisocyanine and Heparin leads to the J-aggregate formation of Pseudoisocyanine on the surface of Heparin, with an exceptional fluorescence enhancement of ∼400 fold. The J-aggregates of Pseudoisocyanine also display remarkable changes in the absorption features, in the presence of Heparin, which provides a unique advantageous feature of dual sensing of Heparin, by colorimetry and fluorimetry. Pseudoisocyanine also displays high selectivity towards Heparin over its structurally related analogs Chondroitin sulphate and Hyaluronic acid, and other analytes, with a detection limit of 2 nM. More importantly, our sensor system shows good performance in the serum samples, a complex biological media. We further demonstrate that, the interaction of Heparin with its only medically approved antidote, Protamine can also be monitored using Pseudoisocyanine J-aggregates. Thus, our assay is sensitive and selective, rapid, simple, and inexpensive, which can promote the Heparin related biochemical and biomedical research.

A new Al3+ selective fluorescent turn-on sensor based on hydrazide-naphthalic anhydride conjugate and its application in live cells imaging

In this communication, we have developed an optical chemosensor 2-amino N-(6-bromo-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)benzamide (NAPH) for selective detection of Al3+ by reacting 4-bromo-1,8-naphthalic anhydride with 2-aminobenzohydrazide. In (DMSO:H2O, 1:1, v/v) medium, the selective and specific nature of NAPH towards Al3+ was observed by the quenching along with a blue-shift in the absorption of NAPH at 465 nm that resulted in the distinct colour change from light brown to colourless. The selective complexation that occurred between NAPH and Al3+ was investigated by 1H NMR and DFT methods. Under similar conditions, the weakly fluorescent receptor NAPH showed a distinct fluorescence enhancement at 555 nm in the presence of Al3+ among the other tested metal ions and anions. The NAPH·Al3+ complex formation is reversible upon addition of strong chelating agent EDTA. The receptor NAPH can be applied to detect Al3+ down to 2.9 μM without any interference from other tested metal ions. In addition, the receptor NAPH was successfully applied to detect Al3+ in live HeLa cells.

1,3-Bis(pyren-1-yliminomethyl)calix[4]arene as a selective fluorescent turn-on sensor for mercury(II) ion

A novel calixarene-based diimine, 1,3-bis(pyren-1-yliminomethyl)calix[4]arene (5), serves as a turn-on-type fluorescent sensor, which selectively detects Hg2+ in THF/H2O (99:1, v/v) in the presence of various other metal ions. Such selectivity is not seen with half salen 1 derived from salicylaldehyde and 1-aminopyrene. 1H NMR analysis reveals that it is a chemodosimetric sensor based on its hydrolysis mediated by Hg2+ to release 1-aminopyrene molecules as fluorescent chromophores.

Highly selective fluorescence turn-on sensor for Cu2+ ions and its application in confocal imaging of living cells

A novel ethylenediamine (EDA) based chemosensor 5 [dimethyl 2,2′-((3-oxocyclohex-1-ene-1,2-diyl)bis(azanediyl))dibenzoate] has been designed and synthesized for the turn on fluorescence sensing of Cu2+ ions. The molecular geometry configuration of 5 is identified by X-ray diffraction and its corresponding orbital electron distributions are predicted by density functional theory (DFT). The probe 5 exhibits strong and selective complexing ability towards Cu2+ over the other metal ions tested in both acetonitrile and aqueous solvent systems. MeCN-HEPES buffer system is more suitable for the selective fluorescence sensing of Cu2+ ions. In addition, the lowest detection limit is 0.30μM for Cu2+ ions. This probe has also been applied successfully for the confocal fluorescence imaging of MDCK cells. Therefore, this probe can be used in both the environmental and biological systems for the detection of Cu2+.

A BODIPY based highly selective fluorescence turn-on sensor toward VIB and IIB metal ions

ABSTRACTA probe for recognition of IIB (Zn2+, Cd2+, and Hg2+) and VIB (Cr3+) was developed based on the framework of BODIPY. The probe was synthesized by attaching DPA to 4-position of BODIPY. It exhibited excellent sensitivity and selectivity function for the IIB and VIB metal ions with 1:1 stoichiometry in acetonitrile solution. The limit of detection of Zn2+, Cd2+, Hg2+, and Cr3+ were obtained by fluorescence “turn-on” and ranged from 20.6 to 23.1 nM. Other metal cations did not interfere with the emission sensing of Zn2+, Cd2+, Hg2+, and Cr3+. The underlying mechanism of fluorescence “turn-on” is based on the intramolecular PET, which controlled the fluorescence “on” or “off.”

A highly sensitive and selective turn-on fluorescence sensor for iodide detection based on newly synthesized oligopyrrole derivative and application to real samples

In this study, we have synthesized and characterized a novel oligopyrrole derivative (5-[1-(4-nitrophenyl)-1H-2-pyrrolyloxyl]-1-phenyl-1H-2-pyrrolol, NPPP) based iodide ion selective fluorescent turn-on sensor. The fluorescent iodide sensor NPPP was synthesized by oxidation reaction of N-phenyl pyrrole with Cu(II) nitrate in acetonitrile. Elemental analysis, MS-spectrometry, 1H NMR, 13C NMR, FT-IR, UV–vis and fluorescence spectrum of NPPP were carried out. A characteristic NPPP fluorescence emission was observed in acetonitrile and water solutions, indicating that the probe is stable in solution and the emission of NPPP was not influenced by the water molecules. NPPP displayed extremely high sensitivity to I− with 3.5-fold fluorescence enhancement by intramolecular charge transfer (ICT) process in the water media. Responses to other anions present in the solution, such as F−, Cl−, Br−, AcO−, NO3−, NO2−, SO42−, S2O52−, ClO4−, IO4−, IO3−, OH− and the effect of pH value on the efficiency of the sensor molecule have also been investigated. NPPP exhibits very good selectivity to iodide ions over various anions interference. Under optimal conditions, its response was linearly proportional to the concentration of I− ions in a range from 1.0×10−7 to 6.0×10−6molL−1 with a detection limit of 9.0×10−8molL−1. The proposed method was successfully applied to the direct determination of I− in real samples such as iodine-fortified salts.

Carbazole phenylthiosemicarbazone-based ensemble of Hg2+ as selective fluorescence turn-on sensor toward cysteine in water

A carbazole-phenylthiosemicarbazone-based open chemosensor has been designed and synthesized, which exhibits high selectivity toward Hg2+ by forming a 1:1 complex. In its Hg2+ensemble, it is reported as a highly sensitive and selective probe for the detection of mercapto biomolecules in aqueous solution. The addition of Cys (Cysteine) to a 99% aqueous solution of carbazole–phenylthiosemicarbazone–Hg2+ ensemble resulted in a rapid and remarkable fluorescence OFF–ON (emission at 436nm). The IMP logic gate has also been generated by choosing Hg2+ and Cys as input and by monitoring the output signal at 436nm that originates from the emission spectra of chemosensor in the presence of Hg2+.

Highly selective fluorescence turn-on sensor for hydrogen sulfide and imaging in living cells

A displacement method of detecting hydrogen sulfide in aqueous media based on complex L–Cu ensemble is developed. Once combined with Cu2+, complex L–Cu displayed high specificity for sulfide anion. Among the various anions, only sulfide anion induce the revival of fluoresecence of compound L, which is quenched by Cu2+, resulting in turn-on type sensing sulfide anion. Complex L–Cu exhibits a highly sensitive fluorescent response toward S2− by releasing compound L to give a remarkable change with 20-fold fluorescence intensity enhancement under 2 equivalent of S2− added in Tris–HCl/ DMF (20mM, 6/4, v/v), and also exhibits a dynamic response range for S2− from 5×10−7 to 5×10−6M, with a detection limit of 0.18μM. In addition, the turn-on fluorescent change upon the addition of S2− is also applied in cell imaging.

A selective fluorescence turn-on sensor for trace vapor detection of hydrogen peroxide

A fluorescence turn-on sensor molecule (C6NIB) has been synthesized and fabricated into a porous matrix to enable trace vapor detection of hydrogen peroxide. The detection limit was projected to be below 5 ppb.

Aqueous Fluorescence Turn-on Sensor for Zn2+ with a Tetraphenylethylene Compound

A new sensitive and selective fluorescence turn-on sensor for Zn(2+) (1) was developed by taking advantage of the aggregation-induced emission of the tetraphenylethylene framework. In addition, the corresponding ester precursor of 1 was successfully used for intracellular Zn(2+) imaging.

Coumarin Dye as Selective Thiourea Sensor

The authors report a highly selective fluorescent turn-on sensor for thioureas. The fluorescence of the coumarin dye is fully quenched by both the carbonyl and bromide functional groups in compound 2, creating a dark sensing background. Intense turn-on response is observed only when both quenchers are removed by the reaction with the target analyte, as in the case of 3-5.

A Highly Selective Fluorescence Turn-on Sensor for Cysteine/Homocysteine and Its Application in Bioimaging

We demonstrated a highly electron-deficient system 1 as a turn-on fluorescence sensor for intracellular imaging of Cys/Hcy in biological samples. On the basis of the specific nucleophilic ability of thiols of Cys and Hcy, 1 exhibited high selectivity and sensitivity for Cys/Hcy over other amino acids and thiol biomolecules. This probe is the first Cys/Hcy sensor with excitation in the visible region and turn-on (75-fold) fluorescence emission and also gives a significant increase in two-photon excited fluorescence for sensing Cys/Hcy. Moreover, confocal laser scanning microscopy and two-photon laser scanning microscopy experiments further established that 1 can be used for sensing Cys/Hcy within biological samples.